Our local Surestart centre has these blocks available for baby play and they are such a big hit with the little ones, it's amazing! I guess it's both the colours and the sounds that engage them.
The set consists of six quality wooden blocks with translucent coloured side panels. Each block is a different colour and contains different beads, which makes different sounds when shaken. All the wooden blocks fit inside another wooden box for easy storage.
The blurb says that the Wonderworld Wooden Rainbow Sound Blocks have no sharp edges, but are sturdy and safe. I tried to make something similar with soda bottles, and it's fine, but no where near as good!
Thanks to wishihadadonkey at HUKD